The reforms, passed in 2011 by Republican lawmakers, severely limit the bargaining power of public sector unions while forcing most state workers to pay more for benefits such as health insurance and pensions. They also made payment of union dues voluntary and forced unions to be recertified every year.

"This case proves, once again, that (the reforms are) constitutional in all respects and that the challenges to the law are baseless," said State Attorney General J.B. Van Hollen.

The laws sparked efforts to recall Wisconsin Governor Scott Walker and some Republican lawmakers who voted for them. Walker survived a recall election last year.

Federal Judge William Conley in Madison wrote in his ruling that the First Amendment grants public employees the right to free speech and association, but does not grant them collective bargaining rights.

"Whatever rights public employees have to associate and petition their public employers on wages and conditions of employment, this right certainly does not compel the employer to listen," Conley wrote in his ruling.

The reforms, which do not apply to public safety workers, do not violate equal protection rights of workers because the government has the right to set wages and benefits for individual workers based on performance and skills, according to Conley.

Katy Lounsbury, an attorney representing the unions in the case, said "it's a wrong decision" and that her clients have yet to decide whether to appeal the ruling.

Similar cases involving the reforms remain in Wisconsin courts. In one case, the state is appealing a ruling by a Madison judge in September 2012, who found the reforms violated workers' right to free speech, association and equal protection.

The reforms also face a challenge in Dane County Circuit Court where oral arguments will be heard in October.